My issue actually has less to do with Snyder (although that's part of it) and more to do with that Watchmen isn't really adaptable. And it's giant storyline certainly can't be fit into a movie. Gilliam wanted to do it as a miniseries, which makes some sense.

In order for it to work, it would have to be on some level about superhero movies the way that Watchmen is about comics. Snyder's not a bright enough director to pull that off.